Heavy
metals normally occur in nature and are essential to life but can become toxic
through accumulation in organisms. Arsenic,
cadmium, chromium, copper, nickel, lead and mercury are the most common heavy
metals which can pollute the environment. Mercury, lead and cadmium are of
greatest concern because of their ability to travel long distances in the atmosphere
(http://www.oceansatlas.org/servlet/CDSServlet?status=ND0xOTE3NSY2PWVuJjMzPSomMzc9a29z).

Sources of heavy metals include mining, industrial
production (foundries, smelters, oil refineries, petrochemical plants,
pesticide production, chemical industry), untreated sewage sludge and diffuse
sources such as metal piping, traffic and combustion by-products from coal-burning
power stations. According to UNEP/GPA (2006a), an increasingly serious global
problem is the management of electronic waste (e-waste), particularly the
disposal of used computers and mobile phones, which contain over 1 000
different materials, many of which are toxic to humans.

Effects

The effects on human health and the environment from
exposure to the three most common heavy metal pollutants (mercury, lead and
cadmium) include:

Mercury accumulation
in fish may harm the fish and other animals that consume them. Birds and
mammals that eat fish are more exposed to mercury than other animals which
live in aquatic ecosystems. Effects on wildlife can include reduced
fertility, damaged kidneys, slower growth and development, abnormal
behavior and even death (http://www.epa.gov/mercury/about.htm). Whales and
dolphins may also be at high risk from mercury exposure (UNEP 2002b).

Lead may, according to UNEP (2008a), cause
neurodevelopmental effects in children, even at low levels of exposure.
Other effects include cardiovascular, renal, gastrointestinal, hematological
and reproductive effects UNEP (2008a). Children six years old and
under are most at risk (http://www.epa.gov/lead/). There is presently no known threshold for the
effects of lead (UNEP 2008a).

In the environment, lead bioaccumulates in most
organisms and is toxic to plants, animals and micro-organisms. Young fish
are more susceptible to lead poisoning than mature fish or eggs. Symptoms
of lead toxicity in fish include spinal deformity and blackening of the
caudal region (rear part of the fish) (UNEP 2008a).

Cadmium is toxic to
humans and exposure can cause pulmonary irritation, kidney disease, bone weakness
and possibly lung, prostate, and
kidney cancer. Food and cigarette smoke are the largest potential sources
of cadmium exposure for the general population (http://www.e-b-i.net/ebi/contaminants/cadmium.html).
According to UNEP (2008b), food
accounts for approximately 90 per cent of Cadmium exposure in the general,
non-smoking population, of which agricultural crops (particularly
irrigated rice) account for most of the intake. Additionally, people with
a high intake of shellfish and organ meat from marine animals may have a
higher intake of cadmium.

Cadmium is also
toxic to plants, animals and micro-organisms. Cadmium accumulates mainly in the
kidney and liver of vertebrates and in aquatic invertebrates and algae (UNEP
2008b). Acute toxic effects on fish, birds and other animals may include death
or fetal
malformations (http://www.e-b-i.net/ebi/contaminants/cadmium.html).
Cadmium can affect plants resulting in decreased growth rate and even death.

Global versus Caribbean Studies on Mercury, Lead and Cadmium

Mercury

According to UNEP (2002b), mercury is one of the most
studied environmental pollutants but there are still gaps in the basic
understanding of its pathways and impacts on human health and environment.
Mercury levels have increased considerably since the beginning of the
industrial age and are now present in the environment and in food all over the
globe. Even regions with few mercury releases, such as the Arctic are affected
due to the global transport. According to Greenpeace (1998), 40 000-80 000
people globally may be suffering from mercury poisoning as a result of the
consumption of contaminated seafood.

Recent studies suggest that anthropogenic
activities have increased the overall level of mercury in the atmosphere by a
factor of 3. In and around industrial areas, the deposition rates have increased by
2 to 10 times during the last 200 years (UNEP 2002b).

Combustion of fossil fuels
and incineration of waste material accounts for approximately 70% of the total
quantified atmospheric emissions from major anthropogenic sources (UNEP 2002b).
Since combustion
of fossil fuels is increasing, mercury emissions can, according to UNEP
(2002b), be expected to increase accordingly. Global climate change may also
have impacts as there have been indications of increased formation of
methylmercury in small, warm lakes and in new flooded areas (http://www.greenfacts.org/en/mercury/l-2/mercury-3.htm#0. According to UNEP (2002b), many countries lack basic
information on the use, release and levels of mercury in the environment.

According to the UN Atlas of the Oceans, high
levels of mercury have recently been recorded in a number of seafood products
including sharks, swordfish, marlins and tunas. Some countries have warned
pregnant women to avoid all consumption of these seafoods.

Lead

Lead is mined in more than 40 countries worldwide and
in 2004 world production of lead was 3
150 000 tonnes (UNEP 2008a). According to UNEP (2008a), lead exposure occurs in
nearly all countries of the world. On a global scale, Latin America, the Middle
East, Asia, parts of Eastern Europe and the Commonwealth of Independent States
are the regions whose peoples have the highest blood levels of lead. According
to Greenpeace (1998), as many as 200 million people globally are at risk of
lead poisoning.

Data from ice core drillings in Greenland
demonstrated that lead levels increased significantly following the industrial
revolution and lead deposited between the 1960s and 1990s was eight times
higher than in pre-industrial times. Nevertheless, since the decreased use of
leaded petrol in the 1970s and the increased emission controls, levels of lead
in ice cores have decreased. According to UNEP (2008a), the global consumption
of lead for manufacturing of petrol additives decreased from 310 000 tonnes in
1970 to 14 400 tonnes in 2003.

According to UNEP (2008a), the quantified
global anthropogenic emissions of lead decreased from 330 000 tonnes to 120 000
tonnes between 1983 and mid-1990s. The total emissions of lead have been
decreasing in most industrialized countries and the release to the aquatic
environment decreased due to improved treatment of wastewater.

However, lack of public awareness and limited
industrial waste management capacity in many developing countries, including
Latin America and small developing island states (SIDS), cause lead containing
products to be inappropriately disposed of. Open burning of waste products
containing lead is probably an important source of local and regional lead
emissions to the atmosphere as well as illegal dump sites and disposal in
wetlands and rivers (UNEP 2008a). The use of lead in some developing countries
has continued or increased in, for example, the the manufacture of plastics and
paints. According to UNEP (2008a), the health effects from lead exposure and
impact on development may cause significant economic losses for society.

Cadmium

Human activities have resulted in elevated cadmium
concentrations in the environment. The global cadmium production has almost
doubled between 1950 and 1990. Since then, the global consumption has remained
constant, at about 20 000 tonnes per year (UNEP 2008b),

Cadmium deposition in the 1960’s and 1970’s, based on
analysis of Greenland ice cores, was eight times higher than in pre-industrial
times. However, according to recent data,
cadmium deposition levels have declined since the 1970’s (UNEP 2008b). Between
1990 and 2003, data show that the anthropogenic emission of cadmium decreased
by an average of 50% in developing countries.

According to UNEP (2008b), a study done in the mid 1990’s
estimated a global anthropogenic atmospheric emission of 2 983 tonnes. The main sources of emissions
are non-ferrous metal production and fossil fuel combustion. Global atmospheric cadmium deposition to the
aquatic environment, originating from anthropogenic sources, is estimated to be
between 900 and 3 600 tonnes (UNEP 2008b).

In some developing countries, the use of cadmium has
continued or increased. Regulations and restrictions are less comprehensive and
hazardous disposal practices like open burning or dumping in rivers and
wetlands have resulted in health and environmental risks (UNEP 2008b). According to Greenpeace (1998), some 250 000-500 000
humans may suffer from renal dysfunction as a result of cadmium exposure.

In agricultural soils, cadmium is mainly deposited through
atmospheric deposition, phosphate fertilizers and sewage sludge. Since plants
are taking up cadmium this can result in an increase concentration in food
products (UNEP 2008b).

Mercury,
Lead and Cadmium in the Wider Caribbean Region

Many of the Central American and Caribbean countries
have high volcanic activity which is a significant natural source of mercury.
While the use of Mercury in fungicides and insecticides has been banned in most
countries of the region it is still produced as a by-product in gold mining,
non metal extraction, dental laboratories and hospitals, fish canning,
municipal waste, mercury lamps, batteries and electrical components (de la Cruz
2002). According to Carré (2002) found in UNEP (2002a), organic mercury
components are imported by paint companies in Haiti. In a Venezuelan gold
mining area, 69% of the miners and 37% of non-miners were contaminated with mercury
in 1990 (UNEP 2002a).

According to UNEP (2008c), leaded gasoline was still
used in Trinidad and Tobago until April 2004. In Panama, lead was added to
petrol until 2001, in Dominican Republic until 1999 and in Guyana until 2000
(UNEP 2002a). At the end of 2005, Cuba prohibited future import and use of Lead
Tetraethyl (UNEP 2008c). However, according to UNEP (2008c), tetraethyl lead in
gasoline is present in 0.44% of the produced gasoline in Cuba. According to
UNEP (2002a), leaded petrol was also banned in Jamaica and Costa Rica but
information regarding this issue was not available for the other countries in
the region. (Leaded gasoline
has actually been phased out in most if not all of the English Speaking
Caribbean Countries as part of that global phase out effort – I am sure we can
find a reference for that somewhere)

A source of lead in all countries within the region is
lead-acid batteries used in vehicles and various industrial applications. In
Trinidad and Tobago slag from a secondary lead smelter was deposited at
landfills and used in road constructions resulting in lead levels as high as
12% around homes and high blood levels of some residents (UNEP 2002a). According to UNEP 2006b coastal areas near to oil
installations show significant heavy metal concentrations in sediments. At the
coast of Santo Domingo (Dominican Republic) and Havana Bay (Cuba), which have
petrochemical complexes in the proximity of the coasts, lead values of up to
113 mg/kg and 340 mg/kg respectively were observed (GEF/UNDP/UNEP 1998, Beltrán et al 2002). Other lead
contaminated sites have been identified in the parishes of St.Catherine
and St.Andrew in Jamaica, where the source was illegal dumping of used lead
acid batteries (Chin Sue 2002).

In the port of Cartagena (Colombia), the
sediments contain heavy metals including copper, cadmium, chromium, lead, zinc
and mercury which have accumulated as a result of previous activities and
discharges. Marine activities like dredging in ports, disturb the polluted
sediments so that they are suspended in the water column where they are
ingested by marine organisms, such as mollusks, and then passed through the
food chain (UNEP et al
2006).

Antifouling paints used on vessels is
also a concern, considering the growing recreational boating sector and
servicing facilities in the region (UNEP 2006b). Antifouling paints, containing copper or tributyltin, discourages the
growth of life on submersed hulls boats.

Laws, Regulations, and Policy Responses on Heavy Metals

According to UNEP (2002a) there is lacking legislation
and regulations concerning the import, export, transport, use, production,
emission, storage and disposal of Persistante Toxic Substances (PTS) including heavy
metals in the region. Ratification of International Conventions relevant to PTS
and harmonization of legislation within the Region has taken place to some
extent (UNEP 2002a).

The most important regional legal framework for the
protection of the Caribbean Sea from pollution is the Convention for the
Protection and Development of the Marine Environment of the Wider Caribbean
Region (Cartagena Convention). The Convention entered into force in 1986 and is
a legally binding, regional multilateral environmental agreement for the
protection and development of the Wider Caribbean Region. The Cartagena Convention deals with reducing pollution by heavy
metals through its Protocol concerning Pollution from Land-based Sources and
Activities (LBS Protocol). In this LBS Protocol, Annex I lists Primary
Pollutants of Concern which includes heavy metals and their compounds. By
ratifying/acceding to the LBS Protocol, governments agree to, e.g. establish
assessment and monitoring programmes, carry out environmental impact
assessments, develop information systems, consider transboundary movements of
pollution, and promote education and awareness for pollution prevention,
reduction and control.

There are a number of International Conventions dealing with
heavy metals:

Convention on Long-Range
Transboundary Air Pollutants (LRTAP), Protocol on Heavy Metals. The aim of the Convention
is that Parties shall endeavor to limit and, as far as possible, gradually
reduce and prevent air pollution including long-range transboundary air
pollution. The Protocol targets three particular harmful metals: mercury,
lead and cadmium. The Protocol entered into force
on 29 December 2003. Read more at http://www.unece.org/env/lrtap/.

Rotterdam Convention on
the Prior Informed Consent (PIC) Procedure for Certain Hazardous Chemicals
and Pesticides in International Trade. Aim to promote shared responsibilities in relation to
importation of hazardous chemicals
and contribute safe use. The Convention entered into force on 24 February
2004. Read more at http://www.pic.int/home.php?type=t&id=5&sid=16.

The Basel Convention on the Control of Transboundary Movements of
Hazardous Wastes and their Disposal. Aims to protect human health and the
environment against the adverse effects resulting from the generation,
management, transboundary movements and disposal of hazardous and other wastes.
It has 170 Parties and came into force in 1992. Read more at http://www.basel.int/.

International Convention
on the Control of Harmful Anti-fouling Systems on Ships. Aim to prohibit
the use of harmful organotins in anti-fouling paints. Will entry into force the 17 September 2008.
Read more at http://www.imo.org/conventions/mainframe.asp?topic_id=529.

What is the Caribbean Environment Programme
(CEP) doing?

The CEP promotes the ratification and implementation
of the LBS Protocol. In collaboration with the UNEP GPA, CEP collaborates with
the Governments of the Wider Caribbean Region in the development and
implementation of National Programmes of
Action (NPAs) for the prevention of pollution from land based sources and
activities. In 2007, direct support was provided to Jamaica, Saint Lucia,
Trinidad and Tobago and Barbados for completion of these plans. Ongoing efforts
are focused on strategic planning and sustainable financing to enable these
NPAs to be mainstreamed into development planning processes and implemented.

In various projects implemented by the CEP, coastal
water quality monitoring is taking place in 2008 and 2009 to establish
environmental baselines and track changes over time and space. Heavy metal
concentrations are measured in coastal waters and sediments of selected
hotspots across the region. LINKS
to projects:

CEP, in collaboration with the Regional Activity
Centre for the LBS Protocol, LBS/RAC-Cimab, is currently updating CEP Technical
Report No. 33, dating from 1994, providing a regional overview of land-based
sources of pollution. The goal is to update with the best available data the
pollutant loadings from industrial, domestic and agricultural sources affecting
the marine environment. This project is to be complete by the end of 2008.

Moreover, CEP has collaboration with the BASEL Convention
in the development of a Used Lead Acid Battery Strategy for Caribbean and in
the promotion of an integrated strategy for managing chemicals and hazardous
wastes. LINKS Additionally
CEP have a formal MOU with the Basel Convention to promote collaboration on
areas of joint interest.CEP is also seeking to strengthen relationships with
the LBS RAC for Cleaner Production based in Barcelona, Spain under the
Barcelona Convention and Mediterranean Action Plan.

What can you do?

Keep yourself informed on
the impacts of heavy metals and products containing them and act
responsibly in their use and disposal.

Always read the labels of products that may
contain heavy metals e.g. paints that may contain lead and follow usage
and disposal instructions carefully.

Protect children
from exposure to all heavy metals since babies and young children are more
sensitive to such toxic substances.

Avoid
mercury-silver dental amalgams.

Only
drink clean water and if possible use a high quality water filtration unit
that removes heavy metal impurities.

Avoid regular
consumption of fish and seafood especially the largest fish (shark, swordfish,
tuna) that may have been exposed to industrial discharges especially those
containing heavy metals This is particularly important for pregnant women
and children.